Exercise equipment has been designed to facilitate a variety of exercise motions and to link such motions to rotation of a crank and/or flywheel. Examples of such equipment include treadmills, which allow a person to walk or run in place; stepper machines, which allow a person to climb in place; bicycle machines, which allow a person to pedal in place; striding machines, which allow a person to move his feet back and forth in reciprocal fashion; and elliptical motion machines, which move a person's feet through a closed curve path of motion. Most such machines operate in one of two general ways, which are described below with reference to a cycling machine for ease of discussion.
Both basic types of cycling machines have a pedal assembly which is connected to a flywheel (by means of a belt, chain, or driveshaft, for example). As the user pedals, inertia is stored in the flywheel and subsequently provides sensations of smoothness and continuance to the exercise motion. In many cases, the flywheel is "stepped up" relative to the pedals to rotate faster and thereby provide greater inertia with less mass.
On a first, relatively traditional type of cycling machine, a one-way clutch is interconnected between the flywheel and the pedal assembly. The clutch causes the pedal assembly to drive the flywheel in a first direction but allows the pedals to rotate freely in a second, opposite direction. As a result, the user can stop pedaling or "coast" at any time, independent of the status of the flywheel.
On a second, relatively contemporary type of cycling machine, a direct drive relationship is established between the flywheel and the pedal assembly. The direct drive constrains the pedals and the flywheel to rotate together or not at all. As a result, any effort to stop the pedals will be resisted by whatever inertia is stored in the flywheel.
An advantage of the more contemporary cycling machine is that flywheel inertia essentially forces a user to continue cycling. A related disadvantage is that the flywheel inertia can present a safety hazard. An object of the present invention is to address this safety concern. Another object of the present invention is to provide a cycling machine which may be "switched" between a "direct drive" machine and a "free wheel" machine. Yet another object of the present invention is to provide accommodating or self-limiting inertia in conjunction with exercise movement.